WIXLIB

COMMANDOPTIONZoom AllZoom CenterZoom DynamicZoom ExtentsZoom PreviousZoom Scale20 P a g eICONDESCRIPTIONThis option causes AutoCAD to display the whole drawing as far as itsdrawing limits (whichever is the greater of the two).This option requires two things: a point that is to be the center of the newdisplay and a value to be its new height in drawing units. The existingheight is the default for the new height to allow for panning across thedrawing. If the new height value is followed by "X" (eg. 2x), then it istaken as a magnification factor relative to the current height. If followedby "XP", then it is taken as a scale factor relative to paper space and canbe used for scaling the contents of paper space viewports.This is a very useful ZOOM option once it is understood. It permits veryquick movement around the drawing. Once selected, this option redrawsthe graphics area of the screen and displays two rectangles. The largerbox shows the extents of the current drawing. The smaller box shows thecurrent view with an "X" in the middle. This moves with the mouse. Thisview box should be positioned so that its lower left corner is at the lowerleft corner of the view required. By pressing the left button on the mouse,the "X" is replaced by an " " pointing to the right side of the view box.This allows you to change the magnification. As the mouse is moved, theview box shrinks and expands so that the size of the required view can beset. The left mouse button toggles between PAN "X" and ZOOM " "mode so that fine adjustments can be achieved. When the view requiredhas been selected, press ENTER or right click to cause AutoCAD todisplay it.This option will display all the graphics that are contained in the drawing(referred to as the drawing extents) with the largest image possible.This option restores the displayed view prior to the current one. For thepurpose of this option, up to 10 views are saved so that the last ten viewscan be recalled. This option includes every time you use the scroll bar,which is one reason to avoid the scroll bars for panning a lot in yourdrawing.This is a 'hidden' default option. You do not have to type "S" to choosethis option. It simply requires the entry of a number that represents amagnification factor. Note that the factor is applied to the entire drawing(as defined by the drawing's limits).Numbers less than 1 will reduce the displayed size of the drawing, whilenumbers greater than 1 will enlarge it. If "X" is inserted after the number(eg. 0.8x) then the factor is applied to the current view. If "XP" is insertedafter the scale factor, then the view is scaled relative to paper space. Thisis useful for zooming a view within a paper space viewport to a specificscale, for example, "1/48XP" will produce a view of model space at ascale of ¼" 1' relative to paper space.

COMMANDOPTIONICONDESCRIPTIONThis option (also a 'hidden' default) prompts the user to pick two cornersof a box on the existing view in order to enlarge that area to fill thedisplay.Zoom WindowZoom Real time provides interactive zooming capability. Pressing ENTER (after entering zoom) on the command line automaticallyplaces you in Real time mode. Hold the left mouse button down at themidpoint of the drawing and move the cursor vertically to the top(positive direction) of the window to zoom in up to 100% (2xmagnification). Hold the left mouse button down at the midpoint of thedrawing and move the cursor vertically to the bottom (negative direction)of the window to zoom out to100% (.5x magnification). You cannot zoomout beyond the extents of the current view.Zoom RealtimeWhen you release the pick button, zooming stops. You can release thepick button, move the cursor to another location in the drawing, and thenpress the pick button again and continue zooming from that location. Toexit Real time Zoom mode, press ENTER or (ESC).Aerial Viewcommand:DSVIEWERAerial View is a zooming tool that displays a view of the drawing in aseparate window so that you can quickly move to that area. If you keepthe Aerial View window open as you work, you can zoom and panwithout choosing a menu option or entering a command. You can changethe view by creating a new view box in the Aerial View window. Tozoom in to the drawing, make the view box smaller by left clicking aNonerectangle. To zoom out of the drawing, make the view box larger. As youzoom in or out of the drawing, a real-time view of the current zoomlocation is displayed in the graphics area. The screenshot shows how theview box looks. Right click in the box and you can move the box towhere you want to zoom to.This option asks you to select an object or objects, then press ENTER and the screen will zoom to those objects only. This is greatfor when you want to work on object.Zoom ObjectZoom InClicking this icon will zoom in to the drawing by about 50%. This optionis only available as an icon and cannot be invoked by the command line.Zoom OutSimilar to 'Zoom In' - this icon will zoom out of your drawing and allowyou to see about 50% more of your drawing space.Mouse ScrollIf you have a scrolling wheel on your mouse, you can use it to zoom inand out of your drawing. Scroll towards you to zoom out and away fromyou to zoom in. You have the option to change the amount of zoom perwheel click with the Zoom factor system variable. Keep in mind that youwill zoom in and out using your mouse location as a 'centre point'.21 P a g e-

COMMAND OPTIONPANCommandICONDESCRIPTIONPanning allows you to quickly move around the drawing area at the samemagnification you currently have set. Type in PAN(orP) ENTER and a hand will appear on the screen. Left click and holdto move around your drawing.KeystrokeIconMenuBoundary HatchBhatch / HDraw HatchHatch EditHatchEdit /HEModify Object Hatch.22 P a g eResultCovers an area with apredefined patternEdits an existing Hatch

WEEK-IISECTIONAL VIEWSOrthographic views when carefully selected may reveal the external features of even the most complicated objects.However, there are objects with complicated interior details and when represented by hidden lines, may not effectivelyreveal the true interior details. This may be overcome by representing one or more of the views ‘in section’.A sectional view is obtained by imagining the object, as if cut by a cutting plane and the portion between the observerand the section plane being removed. Figure. 1 (a) shows an object, with the cutting plane passing through it and Fig.1(b), the two halves drawn apart, exposing the interior details.Fig 1 (a)Fig 1(b)Fig.1.0 Principles of sectioning23 P a g e

[Type text]In order to show such features clearly, one or more views are drawn as if a portion had been cut away to reveal theinterior This procedure is called sectioning and the view showing the cut away picture is called section view.A section is an imaginary cut taken through an object to reveal the shape or interior construction.Fig. 2a shows the imaginary cutting plane in perspective view.The imaginary cutting plane is projected on a standard view so that the sectional view with orthographicrepresentation is obtained as shown in Fig. 2 b .A sectional view must show which portions of the object are solid material and which are spaces. This is doneby section lining (cross-hatching) the solid parts with uniformly spaced thin lines generally at 45º.(a)(b)Fig. 2 sectional view

Types of SectionsDepending on the number of cutting planes, sectional views can be simple with one cutting plane (Fig. 3) orcomplex with two or more cutting planes (Fig.4).If the cutting plane-line cuts entirely across the object, it is called a full section.If the cutting plane cuts halfway through the object, it is a half section.In addition to these, there are broken-out sections, rotated sections, removed sections, auxiliary sections, andassembly sections.Fig.3 sectional views can be simple with one cutting planeFig.4 sectional views can be complex with two or more cutting planes

Exercise No. 8Full SectionA sectional view obtained by assuming that the object is completely cut by a plane is called a full section orsectional view. shown in Fig. 5.1a, in full section. The sectioned view provides all the inner details, better thanthe unsectioned view with dotted lines for inner details (Fig. 5.1b). The cutting plane is represented by its trace(V.T) in the view from the front (Fig. 5.1c) and the direction of sight to obtain the sectional view isrepresented by the arrows.When cutting plane passes fully through an object, it is called full sectionFig. 5 Sectioned and un-sectioned viewsIt may be noted that, in order to obtain a sectional view, only one half of the object is imagined to beremoved, but is not actually shown removed anywhere except in the sectional view. Further, in a sectionalview, the portions of the object that have been cut by the plane are represented by section lining or hatching.The view should also contain the visible parts behind the cutting plane.Figure.6 Full Sectional View

Exercise No. 9Half SectionA half sectional view is preferred for symmetrical objects. For a half section, the cutting plane removes only onequarter of an object. For a symmetrical object, a half sectional view is used to indicate both interior and exteriordetails in the same view.A half section is made by cutting halfway through an object (Fig. 7). Thus, one half is drawn in section andthe other half is a side view, usually, hidden lines are not used (inside details are visible on the section view).Fig. 7 Half SectionAuxiliary sections may be used to supplement the principal views used in orthographic projections. A sectional viewprojected on an auxiliary plane, inclined to the principal planes of projection, shows the cross-sectional shapes offeatures such as arms, ribs and so on. In Fig.8, auxiliary cutting plane X-X is used to obtain the auxiliary section X-X.Fig. 8 Auxiliary section

Exercise No. 10Assembly SectionsAssembly sections consist of a combination of parts.The purpose of an assembly section is to reveal the interior of a machine or structure so that the separate partscan be clearly shown and identified. However, the separate parts do not need to be described.In assembly drawing, only such hidden details (as needed for part identification or dimensioning) are drawn.Fig. 9 Assembly section

Exercise No. 11Hidden Edges and Surface in SectionSections are primarily used to replace hidden lines with visible lines. As a rule, hidden lines and surfaces shouldbe omitted in sectional views.Thus, preferred sectional view should be as in Fig. 10.In some cases, hidden edges and surfaces can be shown for describing the objectFig .10 Hidden Edges and surfaces in section

Section Lining (Cross Hatching)Section lining of a cut surface is indicated by fine lines, which are drawn as continuous lines usually at anangle of 45º with uniform distance (about 2 mm). For smaller or larger areas, distance between lines can befrom 1 mm to 4 mm.Section lining or cross-hatching lines should not be parallel or perpendicular to any main visible linebounding the sectioned area.Fig. 11 Cross HatchingRibs and webs are used to strengthen the parts. When the cutting plane passes through the ribs lengthwise,cross-hatching would give the misleading impression that the section was conical (Fig.12).Therefore, cross-hatching is eliminated from the ribs and webs (as if the cutting plane was just in front ofthem) when the cutting plane passes longitudinally through them (Fig. 12and 13).Fig. 12WebFig. 13 Ribs

Exercise No. 12SPOKES AND ARMS IN SECTIONWhen a cutting plane passes through pulley spokes or arms, cross-hatching is eliminated where theplane is thoughtof as being just in front of the spokes.Even though the cutting plane passes through two of the spokes in Fig. 14, the sectional view in Fig. 14a must be made without cross-hatching the spokes in order to avoid the appearance of a solid web as inFig. 1 4 b.Fig 14 Spokes and Arms

Various cutting planes can be selected for obtaining clear sectional viewsThe plane may cut straight across (Fig.15) or be offset (changing direction forward andbackward) to pass through features.Fig. 15 : Various cutting planes obtaining clear sectional views.

Exercise No. 13Draw (i) sectional view from the front, (ii) the view from above and (iii) the view from the right of theshaft support

Exercise No. 14Draw the (i) the sectional view from the front, (ii) the view from above and (iii) the sectional view fromthe left Of the given Machine block.Isometric View of Machine BlockSectional Views

Exercise No. 15Week-IIIDimensioningA drawing of a component, in addition to providing complete shape description, must also furnishinformation regarding the size description. These are provided through the distances between thesurfaces, location of holes, nature of surface finsih, type of material, etc. The expression of thesefeatures on a drawing, using lines, symbols, figures and notes is called dimensioning.BASIC DIMENSIONINGIn many applications, a drawing should contain annotations showing lengths or distances orangles between objects to convey the desired information. Dimensioning is the process of addingthese annotations to a drawing. AutoCAD provides four basic types of dimensioning; linear,angular, diameter and radius.DIM and DIMI Commands—DIMI command allows executing one dimensioningcommand and then returns to the normal command mode. If several dimensioning commands areto be executed, DIM command should be used. In this mode, the normal set of AutoCADcommands is replaced by a special set of dimensioning commands. To end the process ofdimensioning, EXIT command has to be used.The elements of dimensioning include the projection line, dimension line, leader line, dimensionline termination, the origin indication and the dimension itself. The various elements ofdimensioning are shown in Figs. 1 and 2. The following are some of the principles to be adoptedduring execution of dimensioning:Fig. 1 Elements of dimensioning

Fig. 2 Elements of dimensioningProjection and dimension lines should be drawn as thin continuous lines.Projection lines should extend slightly beyond the respective dimension lines.Projection lines should be drawn perpendicular to the feature being dimensioned. Where necessary,they may be drawn obliquely, but parallel to each other (Fig. 2). However, they must be in contactwith the feature.Projection lines and dimension lines should not cross each other, unless it is unavoidable (Fig.4)A dimension line should be shown unbroken, even where the feature to which it refers, is shownbroken (Fig. 5).A centre line or the outline of a part should not be used as a dimension line, but may be used in placeof projection line (Fig. 6).Fig. 4Fig. 5Fig. 6

Dimension lines should show distinct termination, in the form of arrow heads or oblique strokes or whereapplicable, an origin indication. Two dimension line terminations and an origin indication are shown inFig. 7.Arrow headOblique strokeOrigin indicationFig. 8METHOD–1 (Aligned System)Dimensions should be placed parallel to their dimension lines and preferably near the middle,above and clear-off the dimension line (Fig. 9). An exception may be made where super-imposedrunning dimensions are used (Fig. 15 )Dimensions may be written so that they can be read from the bottom or from the right sideof the drawing. Dimensions on oblique dimension lines should be oriented as shown in Fig. 10.Angular dimensions may be oriented as shown in Fig. 11.Fig. 9Fig. 10 Oblique dimensioningFig. 11 Angular dimensioning

METHOD–2 (Uni-directional System)Dimensions should be indicated so that they can be read from the bottom of the drawing only.Non-horizontal dimension lines are interrupted, preferably near the middle, for insertion of thedimension (Fig. 12). Angular dimensions may be oriented as in Fig. 13Fig. 12Fig. 13 Angular dimensioningArrangement of DimensionsThe arrangement of dimensions on a drawing must indicate clearly the design purpose. Thefollowing are the ways of arranging the dimensions.Chain DimensionsChains of single dimensions should be used only where the possible accumulation of tolerances doesnot endanger the functional requirement of the part (Fig. 14).Fig. 14 Chain dimensioning

Parallel DimensionsIn parallel dimensioning, a number of dimension lines, parallel to one another and spaced -out areused. This method is used where a number of dimensions have a common datum feature (Fig. 15)Fig. 15 Parallel dimensioningCombined DimensionsThese are the result of simultaneous use of chain and parallel dimensions (Fig. 16).Fig. 16 Combined dimensioning

Exercise No. 16DiametersDiameters should be dimensioned on the most appropriate view to ensure clarity. The dimensionvalue should be preceded by φ. Figure 17 shows the method of dimensioning diameters.Chords, Arcs, Angles and RadiiThe dimensioning of chords, arcs and angles should be as shown in Fig. 18. Where the centre ofan arc falls outside the limits of the space available, the dimension line of the radius should bebroken or interrupted according to whether or not it is necessary to locate the centre (Fig. 19).Fig. 18 Dimensioning of chords, arcs and anglesFig. 19 Dimensioning of radius

Equi-distant FeaturesLinear spacings with equi-distant features may be dimensioned as shown in Fig. 20.Fig. 20 Dimensioning equi-distant featuresTapered FeaturesTapered features are dimensioned, either by specifying the diameters at either end and the length,or the length, one of the diameters and the taper or the taper angle (Fig. 21 a).A slope or flat taperis defined as the rise per unit length and is dimensioned by the ratio of the difference between theheights to its length (Fig 21 b).Fig. 21 Dimensioning tapered features

Exercise No. 17EXAMPLESViolations of some of the principles of drawing are indicated in Fig. 22 a. The corrected versionof the same as per the BIS, SP–46: 1988 is given in Fig. 22 b and the reasons are given below:1. Dimension should follow the shape symbol (Fig. 22).2. and 3. As far as possible, features should not be used as extension lines for dimensioning.4. Extension line should touch the feature.5. Extension line should project beyond the dimension line.6. Writing the dimension is not as per the aligned system.7. Hidden lines should meet without a gap8. Centre line representation is wrong. Dot should be replaced by a small dash.9. Horizontal dimension line should not be broken to insert the value of the dimension10. Dimension should be placed above the dimension line11. Radius symbol should precede the dimension12. Centre lines should cross at long dashes13. Dimension should be written by symbol (not abbreviation) followed by its value14. Note with dimensions should be written in capitals.15. Elevation is not the correct usage.16.Usage of the term ‘‘plan’’ is o

AutoCAD. II. Practice the drawing methods for sectioning of joints, couplings, bearings, keys. III. Prepare assembly drawings, sectional views and bill of materials for selected assemblies. LIST OF EXERCISES Week-1 CONVENTIONAL REPRESENTATION Conventional representation of materials